1. Field of the Invention
The present invention relates to an apparatus for securing implanted medical devices and more particularly to an apparatus for securing implanted medical devices such as electrical stimulation leads to various sized cranial burr holes.
2. Description of the Related Art
Medical procedures involving access to the brain through a burr hole in the skull are under increasing use. One such procedure is electrical stimulation of the brain for such purposes as relief of chronic pain and treatment of movement disorders. A typical electrical brain stimulation system comprises generally a pulse generator operatively connected to the brain by a lead having at its distal end at least one electrode designed to be implanted within the brain, and having at its proximal end a connector assembly designed to connect to the pulse generator.
An important aspect of this procedure, and of any other such procedures that involve instrument access to the brain through a burr hole, is the precision with which any such inserted stimulation devices are placed. As can be appreciated, the functional location of the inserted stimulation device is of critical importance and once an inserted device is properly positioned, it is equally important that the device not be moved. Even one millimeter of travel of a properly positioned stimulation device may cause unsatisfactory results. Accordingly, reliable methods and apparatus for stabilizing and fixing the positioned stimulation device in the cranial burr hole are necessary.
Previous designs of systems for securing a positioned device within a burr hole have a number of drawbacks. U.S. Pat. No. 4,328,813 issued to Ray, incorporated herein by reference, discloses a burr hole ring and cap arrangement in which the cap is positioned so as to trap a positioned electrical stimulation lead between the ring and cap by friction. The ring and cap arrangement in Ray, however, is limited by the size of the lead bodies which can be used within a single burr hole ring. Other known burr hole ring and cap assemblies have the same drawbacks. A single burr hole ring can only accommodate a limited size or range of sizes of the lead bodies. The present invention is directed to overcoming these disadvantages of the present burr hole ring and cap anchoring assemblies. Banner & Witcoff, Ltd.